//
// Created by 29019 on 2020/1/4.
//

#include "base64.h"

#include "base64.h"
#include <iostream>
#include <ctype.h>
static const std::string base64_chars =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
      "abcdefghijklmnopqrstuvwxyz"
      "0123456789+/";


static inline bool is_base64(unsigned char c) {
     return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
     std::string ret;
     int i = 0;
     int j = 0;
     unsigned char char_array_3[3];
     unsigned char char_array_4[4];
    
     while (in_len--) {
          char_array_3[i++] = *(bytes_to_encode++);
          if (i == 3) {
               char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
               char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
               char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
               char_array_4[3] = char_array_3[2] & 0x3f;
            
               for(i = 0; (i <4) ; i++)
                ret += base64_chars[char_array_4[i]];
               i = 0;
              }
         }
    
     if (i)
     {
          for(j = i; j < 3; j++)
           char_array_3[j] = '\0';
        
          char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
          char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
          char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
          char_array_4[3] = char_array_3[2] & 0x3f;
        
          for (j = 0; (j < i + 1); j++)
           ret += base64_chars[char_array_4[j]];
        
          while((i++ < 3))
           ret += '=';
        
         }
    
     return ret;
    
}

std::string base64_decode(std::string const& encoded_string) {
     int in_len = encoded_string.size();
     int i = 0;
     int j = 0;
     int in_ = 0;
     unsigned char char_array_4[4], char_array_3[3];
     std::string ret;
    
     while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
          char_array_4[i++] = encoded_string[in_]; in_++;
          if (i ==4) {
               for (i = 0; i <4; i++)
                char_array_4[i] = base64_chars.find(char_array_4[i]);
            
               char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
               char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
               char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
            
               for (i = 0; (i < 3); i++)
                ret += char_array_3[i];
               i = 0;
              }
         }
    
     if (i) {
          for (j = i; j <4; j++)
           char_array_4[j] = 0;
        
          for (j = 0; j <4; j++)
           char_array_4[j] = base64_chars.find(char_array_4[j]);
        
          char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
          char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
          char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
        
          for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
         }
    
     return ret;
}
